232 lines
6.3 KiB
Plaintext
232 lines
6.3 KiB
Plaintext
page ,132
|
|
title strcat - concatenate (append) one string to another
|
|
;***
|
|
;strcat.asm - contains strcat() and strcpy() routines
|
|
;
|
|
; Copyright (c) Microsoft Corporation. All rights reserved.
|
|
;
|
|
;Purpose:
|
|
; STRCAT concatenates (appends) a copy of the source string to the
|
|
; end of the destination string, returning the destination string.
|
|
;
|
|
;*******************************************************************************
|
|
|
|
.xlist
|
|
include cruntime.inc
|
|
.list
|
|
|
|
|
|
page
|
|
;***
|
|
;char *strcat(dst, src) - concatenate (append) one string to another
|
|
;
|
|
;Purpose:
|
|
; Concatenates src onto the end of dest. Assumes enough
|
|
; space in dest.
|
|
;
|
|
; Algorithm:
|
|
; char * strcat (char * dst, char * src)
|
|
; {
|
|
; char * cp = dst;
|
|
;
|
|
; while( *cp )
|
|
; ++cp; /* Find end of dst */
|
|
; while( *cp++ = *src++ )
|
|
; ; /* Copy src to end of dst */
|
|
; return( dst );
|
|
; }
|
|
;
|
|
;Entry:
|
|
; char *dst - string to which "src" is to be appended
|
|
; const char *src - string to be appended to the end of "dst"
|
|
;
|
|
;Exit:
|
|
; The address of "dst" in EAX
|
|
;
|
|
;Uses:
|
|
; EAX, ECX
|
|
;
|
|
;Exceptions:
|
|
;
|
|
;*******************************************************************************
|
|
|
|
page
|
|
;***
|
|
;char *strcpy(dst, src) - copy one string over another
|
|
;
|
|
;Purpose:
|
|
; Copies the string src into the spot specified by
|
|
; dest; assumes enough room.
|
|
;
|
|
; Algorithm:
|
|
; char * strcpy (char * dst, char * src)
|
|
; {
|
|
; char * cp = dst;
|
|
;
|
|
; while( *cp++ = *src++ )
|
|
; ; /* Copy src over dst */
|
|
; return( dst );
|
|
; }
|
|
;
|
|
;Entry:
|
|
; char * dst - string over which "src" is to be copied
|
|
; const char * src - string to be copied over "dst"
|
|
;
|
|
;Exit:
|
|
; The address of "dst" in EAX
|
|
;
|
|
;Uses:
|
|
; EAX, ECX
|
|
;
|
|
;Exceptions:
|
|
;*******************************************************************************
|
|
|
|
|
|
CODESEG
|
|
|
|
% public strcat, strcpy ; make both functions available
|
|
strcpy proc \
|
|
dst:ptr byte, \
|
|
src:ptr byte
|
|
|
|
OPTION PROLOGUE:NONE, EPILOGUE:NONE
|
|
|
|
push edi ; preserve edi
|
|
mov edi,[esp+8] ; edi points to dest string
|
|
jmp short copy_start
|
|
|
|
strcpy endp
|
|
|
|
align 16
|
|
|
|
strcat proc \
|
|
dst:ptr byte, \
|
|
src:ptr byte
|
|
|
|
OPTION PROLOGUE:NONE, EPILOGUE:NONE
|
|
|
|
.FPO ( 0, 2, 0, 0, 0, 0 )
|
|
|
|
mov ecx,[esp+4] ; ecx -> dest string
|
|
push edi ; preserve edi
|
|
test ecx,3 ; test if string is aligned on 32 bits
|
|
je short find_end_of_dest_string_loop
|
|
|
|
dest_misaligned: ; simple byte loop until string is aligned
|
|
mov al,byte ptr [ecx]
|
|
add ecx,1
|
|
test al,al
|
|
je short start_byte_3
|
|
test ecx,3
|
|
jne short dest_misaligned
|
|
|
|
align 4
|
|
|
|
find_end_of_dest_string_loop:
|
|
mov eax,dword ptr [ecx] ; read 4 bytes
|
|
mov edx,7efefeffh
|
|
add edx,eax
|
|
xor eax,-1
|
|
xor eax,edx
|
|
add ecx,4
|
|
test eax,81010100h
|
|
je short find_end_of_dest_string_loop
|
|
; found zero byte in the loop
|
|
mov eax,[ecx - 4]
|
|
test al,al ; is it byte 0
|
|
je short start_byte_0
|
|
test ah,ah ; is it byte 1
|
|
je short start_byte_1
|
|
test eax,00ff0000h ; is it byte 2
|
|
je short start_byte_2
|
|
test eax,0ff000000h ; is it byte 3
|
|
je short start_byte_3
|
|
jmp short find_end_of_dest_string_loop
|
|
; taken if bits 24-30 are clear and bit
|
|
; 31 is set
|
|
start_byte_3:
|
|
lea edi,[ecx - 1]
|
|
jmp short copy_start
|
|
start_byte_2:
|
|
lea edi,[ecx - 2]
|
|
jmp short copy_start
|
|
start_byte_1:
|
|
lea edi,[ecx - 3]
|
|
jmp short copy_start
|
|
start_byte_0:
|
|
lea edi,[ecx - 4]
|
|
; jmp short copy_start
|
|
|
|
; edi points to the end of dest string.
|
|
copy_start::
|
|
mov ecx,[esp+0ch] ; ecx -> sorc string
|
|
test ecx,3 ; test if string is aligned on 32 bits
|
|
je short main_loop_entrance
|
|
|
|
src_misaligned: ; simple byte loop until string is aligned
|
|
mov dl,byte ptr [ecx]
|
|
add ecx,1
|
|
test dl,dl
|
|
je short byte_0
|
|
mov [edi],dl
|
|
add edi,1
|
|
test ecx,3
|
|
jne short src_misaligned
|
|
jmp short main_loop_entrance
|
|
|
|
main_loop: ; edx contains first dword of sorc string
|
|
mov [edi],edx ; store one more dword
|
|
add edi,4 ; kick dest pointer
|
|
main_loop_entrance:
|
|
mov edx,7efefeffh
|
|
mov eax,dword ptr [ecx] ; read 4 bytes
|
|
|
|
add edx,eax
|
|
xor eax,-1
|
|
|
|
xor eax,edx
|
|
mov edx,[ecx] ; it's in cache now
|
|
|
|
add ecx,4 ; kick dest pointer
|
|
test eax,81010100h
|
|
|
|
je short main_loop
|
|
; found zero byte in the loop
|
|
; main_loop_end:
|
|
test dl,dl ; is it byte 0
|
|
je short byte_0
|
|
test dh,dh ; is it byte 1
|
|
je short byte_1
|
|
test edx,00ff0000h ; is it byte 2
|
|
je short byte_2
|
|
test edx,0ff000000h ; is it byte 3
|
|
je short byte_3
|
|
jmp short main_loop ; taken if bits 24-30 are clear and bit
|
|
; 31 is set
|
|
byte_3:
|
|
mov [edi],edx
|
|
mov eax,[esp+8] ; return in eax pointer to dest string
|
|
pop edi
|
|
ret
|
|
byte_2:
|
|
mov [edi],dx
|
|
mov eax,[esp+8] ; return in eax pointer to dest string
|
|
mov byte ptr [edi+2],0
|
|
pop edi
|
|
ret
|
|
byte_1:
|
|
mov [edi],dx
|
|
mov eax,[esp+8] ; return in eax pointer to dest string
|
|
pop edi
|
|
ret
|
|
byte_0:
|
|
mov [edi],dl
|
|
mov eax,[esp+8] ; return in eax pointer to dest string
|
|
pop edi
|
|
ret
|
|
|
|
strcat endp
|
|
|
|
end
|
|
|